The 22" is the viewable area measured in the diagonal angle for a monitor, listing the measurements in the viewable area height x width: 11 5/8" x 18 5/8".
For your specific measurements the closest fit measured at the diagonal 23 1/2" for a 11 1/2" x 20 1/2" size, to fit a 23.6" widescreen.
I will advise you to please have a look at the 3M manufactures site for specific monitor measurements:http://solutions.3m.com/wps/portal/3M/en_US/SDP/Privacy_Filters/Support/One/
I believe the correct privacy filter may be item number 792107 for a 24" Widescreen monitor.
Please also note that for technology it may only be returned within 14 days of the date of receipt. Please feel free to call Staples at 1-800-333-3330, for ordering assistance.
Answered on 6/20/2011 by Laura B from Staples